Crankcase ventilation valve

ABSTRACT

A crankcase ventilation valve for an internal combustion engine having an engine crankcase ventilation system wherein a conduit communicates between the intake and the engine crankcase. The ventilation valve comprises a cylindrical housing having a lateral partition wall, an orifice bored through the partition wall, a rod having a tapered portion axially movable through the orifice and a spring seat secured to the opposite end of the rod, and a coiled spring inserted between the partition wall of the housing and the spring seat of the rod. The rod moves relative to the orifice in response to the balance between the negative pressure at the intake manifold and the elasticity of the coiled spring. When the negative pressure at the intake manifold exceeds a certain predetermined level in magnitude, the coiled spring is compressed to its minimum length by bringing all the adjacent spring turns in contact with each other. Thereby, a suitable minimum flow rate is ensured without necessitating any metallic stopper.

United States Patent [72] Inventor Hideo Horiuchi Yokohama Japan [21] Appl. No. 826,218 [221 Filed May 20, 1969 (45] Patented June 1,1971 [73] Assignee Nissan Jidosha Kabushiki Kaish Yokohama, Japan [32] Priority June 13, 1968 [33] Japan [31 1 43-40317 [54] CRANKCASE VENTILATION VALVE 2 Claims, 6 Drawing Figs.

[52] US. Cl [5 1 1 Int. Cl 1 50] Field of Search [56] References Cited UNITED STATES PATENTS 2,386,765 10/1945 Adams et a1. 3,198,208 8/1965 Tramontini 3,437,082 4/1969 Bouwkampetal. .I:

FOREIGN PATENTS 660,756 4/1963 Canada ABSTRACT: A crankcase ventilation valve for an internal combustion engine having an engine crankcase ventilation system wherein a conduit communicates between the intake and the engine crankcase. The ventilation valve comprises a cylindrical housing having a lateral partition wall, an orifice bored through the partition wall, a rod having a tapered portion axially movable through the orifice and a spring seat secured to the opposite end of the rod, and a coiled'spring inserted between the partition wall of the housing and the. spring seat of the rod. The rod moves relative to the orifice in response to the balance between the negative pressure at the intake manifold and the elasticity of the coiled spring. When the negative pressure at the intake manifold exceeds a certain predetermined level in magnitude, the coiled spring is compressed to its minimum length by bringing all the adjacent spring turns in contact with each other. Thereby, a suitable minimum flow rate is ensured without necessitating any metallic stopper.

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mm Ha,lnabaaMa value I 1 l I l l l ,0 I00 200 300400500600 700 Nagaflva praaaura at lmaka manifold mml-lg,ln absolute valua CRANKCASE VENTILATION VALVE This invention relates to a crankcase ventilation valve, and more particularly to a crankcase ventilation valve having a coiled spring with aplurality of spring turns and inserted between an orifice and a spring seat, said turns being brought into tight contact with each other when a certain negative pressure is produced at the engine intake manifold, so as to ensure the minimum passage of air through the orifice by such contact of the adjacent turns of the coiled spring. The crankcase ventilation valve according to the present invention is especially suitable for engine having a very small number of cylinders.

A known crankcase ventilating system usually includes a crankcase ventilation valve having a rod and a spring for controlling the flow rate of air in response to the variation of negative pressure at the intake manifold of the engine. If such crankcase ventilation valve of known construction is mounted on an internal combustion engine having only a very small number of cylinders, the frequency of pulsation of the intake air pressure is comparatively low and it becomes very close to or almost identical with the natural frequency of a vibrating system consisting of the rod and the spring of the crankcase ventilation valve. Accordingly, the known crankcase ventilation valve mounted on such internal combustion engine is frequently subjected to severe vibration, and it is sometimes difficult to effect satisfactory control of air flow. Furthermore, such vibration accelerates the abrasion of the rod, the spring, and the orifice formed integrally with the housing of the crankcase ventilation valve.

In order to eliminate the aforesaid resonance between the crankcase ventilation valve and the pulsation in the air pressure at the intake manifold, it is preferable to select the natural frequency of the ventilation valve substantially lower than any foreseeable pulsating frequency of the intake air pressure of the engine intake manifold. To this end, it is effective to increase the weight of the valve rod and to reduce the elasticity of the spring cooperating with the valve rod. However, if the weight of the valve rod is increased without modifying its diameter, the rod inevitably becomes longer and the overall dimension of the crankcase ventilation valve becomes larger. Such long rod requires an elongated contact surface between the rod and the spring in the ventilation valve, which causes an accelerated abrasion of the spring and the rod.

Generally speaking, crankcase ventilation valves are required to produce a constant flow rate of air when the engine load is low. Accordingly, it is possible to shorten the stroke of the rod by holding the rod at a position corresponding to the desired constant flow rate, as long as the desired constant flow rate is achieved. If the stroke of the rod can be thus limited, the ventilation valve can be made compact. With the shorter control stroke of the rod, the distance through which the rod slides in contact with the spring surface and the orifice of valve housing can be also reduced, so that abrasion can be greatly reduced at the rod, the spring and the housing A typical known crankcase ventilation valve, designed by considering the aforesaid factors, was disclosed by W. D. Pittsley in his US. Pat. No. 3,359,960, issued on Dec. 26, I967. The ventilation valve of Pittsley, however, uses a metallic stopper, for limiting the movement of a flow rate controlling rod, so as to provide a well defined minimum air flow rate through the ventilation valve. If such known ventilation valve using a metallic stopper is mounted on an engine having a very small number of cylinders, the rod strikes the stopper rather frequently under certain operative conditions, and the metallic sounds produced by such striking become annoying to the drivers. Furthermore, such striking of the metallic stopper by the rod tends to accelerate fatigue of the material of such rod and stopper, which might lead to a shortened service life of the ventilation valve.

Therefore, an object of the present invention is to obviate the aforesaid difficulties of known crankcase ventilation valves for use in an engine crankcase ventilation system wherein a conduit communicates between the engine crankcase and the air intake manifold for the cylinder by providing an improved crankcase ventilation valve having a coiled spring, said coiled spring consisting of a plurality of turns which are brought into tight contact with each other when the negative pressure at the intake manifold of the internal combustion engine exceeds a certain predetermined level in absolute value, so as to compress the coiled spring to its minimum length. By using such coiled spring, the stroke of the rod can be limited by the coiled spring itself without necessitating any metallic stopper.

It is another object of the present invention to provide a crankcase ventilation valve which can be operated quietly without causing any metallic noise due to collision of metallic parts with each other.

Another object of the present invention is to provide a crankcase ventilation valve for use in an engine crankcase ventilating system, which is capable of enduring a long service life by eliminating parts liable to frequent collision with each other.

For a better understanding of the invention, reference is made to the accompanying drawings, in which:

FIG. 1 is a diagrammatic illustration of the manner in which a crankcase ventilation valve according to the present invention is mounted on an internal combustion engine;

FIG. 2 is a sectional view of a crankcase ventilation valve according to the present invention, illustrating its operation when the engine equipped with the ventilation valve is heavily loaded;

Flg. 3 is an end view of the crankcase ventilation valve, as seen from the right hand of FIG. 2;

FIG. 4 is a sectional view similar to FIG. 2, illustrating the operation of the crankcase ventilation valve when the related engine is lightly loaded;

Flg. 5 is a graph, illustrating the flow rate characteristics of a crankcase ventilation valve according to the present invention; and

FIG. 6 is a graph, showing amplitude characteristic of rod movement in the crankcase ventilation valve of the present invention in comparison with that of a known ventilation valve.

Like parts and members are designated by like numerals and symbols throughout the drawings.

FIG. 1 is a schematic diagram, illustrating an internal combustion engine having a crankcase ventilation valve of the present invention mounted thereon. Fresh air from an air cleaner 2 is fed to a crankcase 6 through a hose 4 and a rocker cover 5, so as to refresh the air in the crankcase 6. A crankcase ventilation valve 1 according to the present invention is disposed in an engine crankcase ventilating system, wherein a conduit 7 communicates between the crankcase 6 and an intake manifold 8 for the engine, in such manner that the vapor in the crankcase, including blowby gas, can be fed to the intake manifold through the ventilation valve at a controllable rate.

FIG. 2 is a longitudinal sectional view of a ventilation valve 1 according to the present invention, shown in the state as assumed when an engine equipped with the ventilation valve is heavily loaded. FlG. 3 is an end view taken from the right hand of FIG. 2. Referring to FIG. 2, the ventilation valve 1 comprises a housing ll with a lateral partition wall 11a; a rod 13 having a body 13a, a tapered metering portion 14 at one end of the body 13a, and a spring seat 15 integrally secured to the opposite end thereof; a.coiled spring 17 inserted between the partition wall lla of the housing 11 and the spring seat 15 of the rod 13; and an annular washer 18 mounted at the right hand end of the housing 11 by a snap ring 19. A circular orifice 12 is coaxially bored through the partition wall 11a of the housing 11, so that the rod 13 can coaxially move back and forth through the orifice with a clearance therefrom. The spring seat 15 has four notches formed on its periphery for facilitating air passage therethrough. The tapered metering portion 14 has a large diameter portion 14b adjacent the body 13a of the rod and a small diameter portion 14a at the free end, as seen in FIG. 2. The diameter of the orifice 12 is selected to be larger than that of the large diameter portion 14b of the rod. Accordingly, the orifice diameter is larger than that of the small diameter portion 140.

The aforesaid notches 15a form end openings of an air passage 16 defined between the peripheral surface of the rod 13 and the inner surface 17a of the spring 17. As a result, when the spring 17 is compressed to bring all the adjacent spiral turns in tight contact with each other, the air from the crankcase 6 enters into the air passage 16 through the openings at the notches 15a and reaches an air gap between the orifice 12 of the housing 11 and the tapered metering portion 14 of the rod 13, as shown by arrows of FIGS. 2 and 4. The outermost peripheral surface of the spring seat 15 slidingly engages the inner peripheral surface of the housing 11, and the configuration of the orifice 12 and the tapered metering portion 14 is such that the metering portion 14 slidingly fits in the orifice 12 with a varying clearance therebetween. In other words, the rod 13 is supported by the housing 11 at the spring seat 15 and at the metering portion 14.

The washer 18 is for preventing the propagation of backfire, and the snap ring 19 is fitted in a cooperating annular groove 190 formed on the inner wall of the housing 11 to facilitate the removal of the washer 18 from the ventilation valve for cleaning and for replacement. It is also possible to mount the washer 18 to the housing 11 by any other suitable means, such as a cap nut.

When the engine equipped with the ventilation valve 1 according to the present invention is heavily loaded, the rod 13 is held at the position as shown in FIG. 2, due to the balance of pneumatic forces acting on the rod 13 and the elastic force of the coiled spring 17. The air from the engine crankcase 6 streams through the ventilation valve 1, as shown by the arrows 30 in the figure. The flow rate of such air stream is controlled by varying the magnitude of the clearance at the gap 20 between the orifice 12 and the metering portion 14 of the rod 13. In other words, as the engine speed varies, the spring 17 expands or contracts so as to change its elastic force for establishing a new balance with the thus varied negative pressure at the intake manifold. As the length of the spring 17 varies the rod 13 moves relative to the housing 11, so that the tapered metering portion 14 moves relative to the orifice 12 and the magnitude of the clearance between the orifice 12 and the metering portion 14 changes due to the taper of the metering portion 14. Thus, the flow rate of the air through the ventilation valve 1 varies in response to the change in the negative pressure at the engine intake manifold.

FIG. 5 shows the relation between the flow rate of air through the ventilation valve 1, as represented on the or dinate, and the negative pressure at the intake manifold, as represented on the abscissa. In the range between points B and C of the figure, as the negative pressure at the intake manifold decreases (i.e., increases in its absolute value), the air flow rate through the ventilation valve 1 decreases. In other words, when the negative pressure at the intake manifold decreases in the range F6, the rate of engine exhaust gas discharge or blowby gas is also reduced, and at the same time, the rod 13 of the ventilation valve 1 moves leftwards to reduce the effective gas-flow area of the clearance 20 for decreasing the air flow rate through the valve 1, in response to such reduction in the negative pressure at the intake manifold.

Hg. 4 is a view similar to FIG. 2, illustrating the position of the rod 13 and the spring 17 when the engine equipped with the ventilation valve 1 is lightly loaded. In this case, the movement of the rod 13 is limited at a position where the spring 17 is compressed to its minimum length. The air flow rate is determined by the air gap 20, which is now defined by the orifice l2 and the large diameter portion 14b of the rod. Accordingly, the magnitude of the clearance at the air gap 20 is kept constant even when the negative pressure at the engine intake manifold further increases. As a result, air flow rate through the ventilation valve is also kept constant. In fact, the

air velocity in the ventilation valve 1 corresponding to the point C of FIG. 5 is close to the velocity of sound, and the air velocity or flow rate through the ventilation valve 1 is constant for negative pressure smaller than that at the point C, as illustrated by the line Glj in the figure.

In the preceding description, although the ventilation valve 1 is disposed horizontally, the present invention is not restricted to such horizontal disposition. In fact, the ventilation valve of the present invention can be disposed vertically or at any angular positions.

With the ventilation valve of the aforesaid construction, the rod 13 will not vibrate even when the negative pressure at the engine intake manifold pulsates, because the spring 17 is held at its minimum length by keeping all the adjacent spiral turns in contact with each other as long as the negative pressure at the intake manifold is in the range (T5 of FIG. 5, and the rod 13 is held stationary even if the intake manifold pressure varies in the range GD.

FIG. 6 is a graph showing the amplitude of the movement of rod 13 ofa known ventilation valve in comparison with that of a ventilation valve of the present invention, in which the dashdot curve X represents the amplitude of a known ventilation valve. The curve X shows clearly that the amplitude of the known ventilation valve monotonously increases as the negative pressure at the intake manifold reduces. Accordingly, the known ventilation valve cannot avoid the resonance of the rod movement with the pressure pulsation at the engine intake manifold. On the other hand, according to the present inven tion, the amplitude of movement of the rod 13, as shown by a solid line Y in FIG. 6, is limited to a certain value, which is reached by the rod 13 when the negative pressure at the intake manifold decreases to a certain level. The amplitude of the rod 13 of the ventilation valve according to the present invention is kept at said certain value or lower. Therefore, the rod 13 never comes into resonance with any pulsation of practically significant frequency in the negative pressure at the intake manifold of the engine.

Furthermore, the coiled spring 17 is used in such manner that its adjacent spiral turns are brought into tight contact with each other when the rod 13 comes to its extreme left position. In other words, the coiled spring 17 acts as a cushion to absorb the kinetic energy of the rod 13 when the latter comes to its extreme left position. As a result, the magnitude of the metallic noise caused by striking of the housing 1, or a stopper, of known construction by the rod 13, can be greatly reduced. The elimination of a metallic stopper also results in an improved stability of operative characteristics and an elongated service life of the ventilation valve.

In the illustrated embodiment, the outer peripheral surface of housing 11 is threaded in the proximity of the outlet, as shown by 25, for facilitating mounting of the ventilation valve on the intake manifold of the engine by screwing. An annular projection 29 is formed on the outer peripheral wall of the housing 11 in the proximity of the inlet, to facilitate the engagement between the housing and a hose or tube communicating the housing with the crankcase.

Iclaim:

l. A crankcase ventilation valve for use in an engine crankcase ventilating system having a conduit communicating between the engine crankcase and the air intake manifold, comprising, a cylindrical housing having an inlet and an outlet, a laterally positioned partition wall located downstream of said housing near the outlet thereof, said partition wall having an orifice opening therethrough, said orifice opening being positioned concentrically with said cylindrical housing, a valve element movably located within said housing and positioned upstream of said orifice, said valve element having one end thereof tapered for cooperation with said orifice to regulate gas flow through said orifice, and having a disc-shaped spring seat formed at the other end thereof upstream of said orifice, a coil spring positioned between said partition wall and said disc to bias said valve element away from said orifice, said coiled spring having an inside diameter greater than the diameter of said valve element and less than the diameter of said discshaped spring seat, said disc-shaped spring seat having at least one notch in the periphery thereof defining an axial gas flow passage between said valve element and said spring, the minimum compressed length of said spring being sufficient to prevent complete blockage of said orifice by said tapered valve element, whereby when the pressure differential across said valve seat is further increased beyond a predetermined value, the valve element will be prevented from completely blocking said orifice so as to cause the gas flow rate through said valve to remain substantially constant upon further increase of the pressure differential across said valve element and to prevent pulsation of said valve element.

2. In an engine crankcase ventilating system having a conduit communicating said engine crankcase with the engine air intake manifold, a crankcase ventilation valve adapted to be positioned in said conduit comprising, an inlet opening communicating with said crankcase, an outlet opening communicating with said air intake manifold, a hollow cylindrical housing extending between said inlet and outlet openings, said hollow cylindrical housing having a partition wall laterally formed therein, a circular orifice opening through said partition wall and positioned concentrically with said hollow cylindrical housing for facilitating gas flow therethrough, a rod movably disposed within said housing in axial alignment with said orifice opening, a spring seat secured to one end of said rod, said spring seat having a diameter larger than that of said rod and smaller than the inside diameter of said housing, a plurality of notches formed on the periphery of said spring seat, said rod being tapered from a longitudinally intermediate point along the length thereof to the end opposite said spring seat, said tapered portion being such that the diameter of the rod diminishes in the direction away from said intermediate point, a coiled spring positioned between said partition wall and said valve seat, said coiled spring loosely encircling said rod for biasing said rod away from said orifice, said coiled spring having a length determined by the balance between the negative pressure at the intake manifold and the elastic force of said coiled spring so as to move said rod relative to said orifice in response to the variation of the negative intake manifold pressure, said notches in the periphery of said spring seat defining axial gas flow passages between said rod and said spring, said coiled spring being formed with spiral turns adapted to be brought into contact with each other when said coiled spring is compressed to its minimum length when the negative pressure in said intake manifold reaches a predetermined value, whereby said minimum length of said compressed coiled spring will limit the movement of said rod toward said partition wall to prevent complete blockage of gas flow through said partition wall while limiting the maximum amount of flow therethrough. 

1. A crankcase ventilation valve for use in an engine crankcase ventilating system having a conduit communicating between the engine crankcase and the air intake manifold, comprising, a cylindrical housing having an inlet and an outlet, a laterally positioned partition wall located downstream of said housing near the outlet thereof, said partition wall having an orifice opening therethrough, said orifice opening being positioned concentrically with said cylindrical housing, a valve element movably located within said housing and positioned upstream of said orifice, said valve element having one end thereof tapered for cooperation with said orifice to regulate gas flow through said orifice, and having a disc-shaped spring seat formed at the other end thereof upstream of said orifice, a coil spring positioned between said partition wall and said disc to bias said valve element away from said orifice, said coiled spring having an inside diameter greater than the diameter of said valve element and less than the diameter of said disc-shaped spring seat, said disc-shaped spring seat having at least one notch in the periphery thereof defining an axial gas flow passage between said valve element and said spring, the minimum compressed length of said spring being sufficient to prevent complete blockage of said orifice by said tapered valve element, whereby when the pressure differential across said valve seat is further increased beyond a predetermined value, the valve element will be prevented from completely blocking said orifice so as to cause the gas flow rate through said valve to remain substantially constant upon further increase of the pressure differential across said valve element and to prevent pulsation of said valve element.
 2. In an engine crankcase ventilating system having a conduit communicating said engine crankcase with the engine air intake manifold, a crankcase ventilation valve adapted to be positioned in said conduit comprising, an inlet opening communicating with said crankcase, an outlet opening communicating with said air intake manifold, a hollow cylindrical housing extending between said inlet and outlet openings, said hollow cylindrical housing having a partition wall laterally formed therein, a circular orifice opening through said partition wall and positioned concentrically with said hollow cylindrical housing for facilitating gAs flow therethrough, a rod movably disposed within said housing in axial alignment with said orifice opening, a spring seat secured to one end of said rod, said spring seat having a diameter larger than that of said rod and smaller than the inside diameter of said housing, a plurality of notches formed on the periphery of said spring seat, said rod being tapered from a longitudinally intermediate point along the length thereof to the end opposite said spring seat, said tapered portion being such that the diameter of the rod diminishes in the direction away from said intermediate point, a coiled spring positioned between said partition wall and said valve seat, said coiled spring loosely encircling said rod for biasing said rod away from said orifice, said coiled spring having a length determined by the balance between the negative pressure at the intake manifold and the elastic force of said coiled spring so as to move said rod relative to said orifice in response to the variation of the negative intake manifold pressure, said notches in the periphery of said spring seat defining axial gas flow passages between said rod and said spring, said coiled spring being formed with spiral turns adapted to be brought into contact with each other when said coiled spring is compressed to its minimum length when the negative pressure in said intake manifold reaches a predetermined value, whereby said minimum length of said compressed coiled spring will limit the movement of said rod toward said partition wall to prevent complete blockage of gas flow through said partition wall while limiting the maximum amount of flow therethrough. 